K Gray
Published © MIT

Bike GPS Speedometer using the DFRobot Bluno and TFT Screen

This tutorial is for how to make a simple bike GPS speedometer (and much more) using DFRobot's Bluno, TFT screen, and GPS.

BeginnerFull instructions provided1 hour169
Bike GPS Speedometer using the DFRobot Bluno and TFT Screen

Things used in this project

Hardware components

DFRobot Bluno
I never got the Bluno to work for this application. The DFRobot Uno would work just fine.
×1
DFRobot 3.5" TFT LCD Touchscreen
×1
DFRobot GPS Module with Enclosure
×1

Software apps and online services

Arduino IDE
Arduino IDE

Story

Read more

Schematics

Bluno To Display Schematic

Bluno To GPS Schematic

Code

GPS_Speedometer.ino

C/C++
#include <DFRobot_GDL.h>
#include <TinyGPS++.h>
#include <SoftwareSerial.h>

//display
#define TFT_DC  8
#define TFT_CS  10
#define TFT_RST 9

#define arrSize(X) sizeof(X) / sizeof(X[0])

int last = 0;

float LAT;
float LON;

float topSpeed;
float Speed;
float Course;
float Alt;
float aveSpeed;
float aveSpeeds;
int Sat;

//GPS
static const int RXPin = 3, TXPin = 2;
static const uint32_t GPSBaud = 9600;

int bearings[] =               { 0,    22.5,  45,   67.5,  90, 112.5,  135,  157.5, 180,  202.5, 225,  247.5, 270, 292.5,  315, 337.5, 360 };
const char* bearingStrings[] = { "N", "NNE", "NE", "ENE", "E", "ESE", "SE",  "SSE", "S",  "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW", "N" };

DFRobot_ILI9488_320x480_HW_SPI screen(TFT_DC,TFT_CS,TFT_RST);
TinyGPSPlus gps;
SoftwareSerial ss(RXPin, TXPin);

#define screenColor COLOR_RGB565_NAVY
#define backColor COLOR_RGB565_DGRAY

double HOME_LAT;
double HOME_LON;

void setup() {  
  Serial.begin(115200);
  
  ss.begin(GPSBaud);
  
  screen.begin();
  screen.setRotation(1);
  screen.fillScreen(COLOR_RGB565_WHITE);
  screen.setTextColor(COLOR_RGB565_RED);
  
  retry:
  while (ss.available() > 0){
    gps.encode(ss.read());
  }

  while (!gps.location.isUpdated()){
    screen.setCursor(190,150);
    screen.print("No GPS Data");
    goto retry;
  }
  
  HOME_LAT = gps.location.lat();
  HOME_LON = gps.location.lng();

  screen.fillRoundRect(0, 0, 480, 320, 15, backColor);
  screen.fillRoundRect(7, 7, 466, 306, 15, screenColor);

  //title
  screen.setTextColor(COLOR_RGB565_CYAN);
  screen.setTextSize(3);
  screen.setCursor(70, 13);
  screen.print("GPS Speedometer");

  screen.setTextSize(1);

  //title underline
  screen.drawLine(20, 50, 460, 50, 0x0700);

  //speed
  screen.drawRoundRect(30, 60, 205, 65, 15, 0x0700);
  screen.setCursor(200,64);
  screen.print("MPH");

  //course
  screen.drawRoundRect(245, 60, 205, 65, 15, 0x0700);
  screen.setCursor(415,64);
  screen.print("DEG"); 
  
  //altitude
  screen.drawRoundRect(30, 135, 205, 65, 15, 0x0700);
  screen.setCursor(200,140);
  screen.print("FT");
  
  //direction
  screen.drawRoundRect(245, 135, 205, 65, 15, 0x0700);
  screen.setCursor(415,140);
  screen.print("ROS");
  
  //top speed
  screen.drawRoundRect(30, 210, 205, 45, 15, 0x0700);
  
  //direction (left or right)
  screen.drawRoundRect(245, 210, 205, 45, 15, 0x0700);
  
  //course to home
  screen.drawRoundRect(30, 265, 205, 45, 15, 0x0700);
  
  //dist to home
  screen.drawRoundRect(245, 265, 205, 45, 15, 0x0700);

  last = millis();
}

void loop(){
  screen.setTextColor(COLOR_RGB565_GREEN);
  screen.setTextSize(3);

  while (ss.available() > 0){
    gps.encode(ss.read());
  }

  if (gps.location.isUpdated()){
    LAT = gps.location.lat();
    LON = gps.location.lng();
  }

  if (gps.speed.isUpdated()){
    Speed = gps.speed.mph();
    if (gps.speed.mph() < 1){
      Speed = 0;
    }
  }

  if (gps.course.isUpdated()){
    Course = gps.course.deg();
  }

  if (gps.altitude.isUpdated()){
    Alt = gps.altitude.feet();
  }
  
  if (gps.satellites.isUpdated()){
    Sat = gps.satellites.value();
  }

  if (millis() - last > 1000){
    displayData();
    last = millis();
  }
}

int nearestBearing(int x, bool sorted = true) {
  int idx = 0; // by default near first element
  int distance = abs(bearings[idx] - x);
  for (int i = 1; i < arrSize(bearings); i++) {
    int d = abs(bearings[i] - x);
    if (d < distance) {
      idx = i;
      distance = d;
    }
    else if (sorted) return idx;
  }
  return idx;
}

void displayData(){
  screen.setTextColor(COLOR_RGB565_GREEN);
  screen.setTextSize(3);
  
  //speed
  screen.fillRect(110,78,120,25,screenColor);
  screen.setCursor(45, 80);
  screen.print("SPD: ");
  screen.println(Speed);

  //course
  screen.fillRect(325,78,120,25,screenColor);
  screen.setCursor(260, 80);
  if (Course >= 100){
    screen.print("CSE:");
  }
  else {
    screen.print("CSE: ");
  }
  screen.println(Course);

  //altitude
  screen.setCursor(45, 155);
  if (Alt >= 100 && Alt < 1000){
    screen.fillRect(110,153,120,25,screenColor);
    screen.print("ALT:");
  }
  else if (Alt >= 1000){
    screen.fillRect(70,153,160,25,screenColor);
    screen.print("A: ");
  }
  else {
    screen.fillRect(110,153,120,25,screenColor);
    screen.print("ALT: ");
  }
  screen.println(Alt);

  //direction
  screen.fillRect(330,153,80,25,screenColor);
  screen.setCursor(260, 155);
  screen.print("DIR: ");
  screen.println(bearingStrings[nearestBearing(Course)]);
  
  //top speed
  if (Speed > topSpeed){
    topSpeed = Speed;
    screen.fillRect(92,223,135,25,screenColor);
    screen.setCursor(45, 225);
    screen.print("TS: ");
    screen.print(topSpeed);
  }

  double distanceToHome =
        TinyGPSPlus::distanceBetween(
          gps.location.lat(),
          gps.location.lng(),
          HOME_LAT, 
          HOME_LON) / 1000;
  double courseToHome =
        TinyGPSPlus::courseTo(
          gps.location.lat(),
          gps.location.lng(),
          HOME_LAT, 
          HOME_LON);
  double distanceToHomeFT = distanceToHome*3281;
  
  Serial.println(distanceToHomeFT, 6);
  Serial.println(courseToHome, 6);
  
  screen.fillRect(307,223,135,25,screenColor);
  screen.setCursor(260, 225);
  screen.print("D: ");
  if (turnRight(Course,courseToHome) == true){
    Serial.println("Right");
    screen.print("Right");
  }
  else if (turnRight(Course,courseToHome) == false){
    Serial.println("Left");
    screen.print("Left");
  }
   
  screen.setTextSize(2);
    
  screen.fillRect(90,278,140,18,screenColor);//screenColor
  screen.setCursor(45, 280);
  screen.print("Dist:");
  screen.println(distanceToHomeFT, 2);//in feet
    
  screen.fillRect(305,278,140,18,screenColor);
  screen.setCursor(260, 280);
  screen.print("CSE:");
  screen.println(courseToHome, 1);

  screen.setTextSize(3);

  //satellites
  screen.setTextColor(COLOR_RGB565_WHITE);
  screen.setTextSize(2);
  screen.fillRect(435,10,28,18,screenColor);
  screen.setCursor(390, 12);
  screen.print("SAT:");
  screen.println(Sat);
}

bool turnRight(long CourseNow,long CourseNew){
  bool retval = true;  
  if(CourseNew > CourseNow){
    if((CourseNew-CourseNow) > 180)
      retval = false;
    }
  else {
    if((CourseNow-CourseNew) < 180){
      retval = false;
    }
  }
  return retval;    
}

GPS_Speedometer.ino

Credits

K Gray

K Gray

14 projects β€’ 8 followers
I love making things out of electronic components, coding in python and C++, designing PCBs and lots more.
Thanks to DFRobot.

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